Save, Options PNG / PBM/PGM/PPM / ICO
Set the compression level and transparent color (similar to GIF/ICO) for PNG images. Note: PNG is a lossless format (like GIF) with true color support. It is usually the ideal format for screenshots, because the file size for this images is often much smaller as i.e. JPG, the saved image has at the same time no loss in quality and can be read by many programs.
Save transparent color: after you click on the Save button, a preview dialog will be showed to click into the preview image to set the transparent color.
You can also try the PNGOUT PlugIn for optimized PNG saving. It can reduce the result file size.
PBM, PGM, PPM
You can save transparent ICO images with the click on the preview image during the saving.
After setting the options you choose, click Save to save the image and store the settings. To exit without saving the file or changed options, click Cancel.
The new settings will stay in effect until you change them again.